1. Field of the Invention
This invention generally relates to surgical access devices and, in particular, to a self-sealing cannula having integrated seals.
2. Discussion of the Relevant Art
Access devices used in laparoscopic surgery generally include a cannula providing an operative channel that traverses a body wall and extends into an associated body cavity. The cannula is generally equipped with a proximal seal housing that remains external to the body cavity. The seal housing generally contains a combination of seal members sized and configured to maintain an elevated pressure within the body cavity.
The most common seal construction within the seal housing comprises a first seal sized and configured to maintain a pressure differential when an instrument or tool is within the cannula and seal housing. This type of seal is commonly known as a septum seal. A typical septum seal is an elastomeric sheet or form with a hole or piercing generally at the center. A septum seal is generally dedicated to a range of instruments or tools, such as from five millimeters to twelve millimeters. To complete the seal system of a typical cannula seal-housing, a zero seal or zero seal is normally employed. Zero seals or zero seals are generally configured to be either open or closed and often rely on gradient pressure to form a complete seal. Examples of such zero seals or zero seals may include flap-valves, ball-zero seals and duckbill valves. The septum seal is preferably located proximal of the second seal so that an instrument or tool blocks the orifice in the septum before breaching the second seal or zero seal.
The cannulas and seal housings are generally constructed of rigid materials. The most common material is plastic for disposable devices and metal for reusable devices. The seal housing extends for a distance proximally and is generally quite wider in diameter than the cannula. A typical cannula is approximately 100 mm long and a typical seal housing is 20-50 mm in length. The diameter of a typical cannula will accommodate instruments in the range of five millimeters to twelve millimeters. The diameter of the respective seal housings may range from twenty millimeters for a five-millimeter cannula to thirty millimeters for a twelve-millimeter cannula.
Disadvantages of large seal housings include higher weight, cost and the limitation they place on the full use of surgical instruments passing through the seal housings. For instance, a surgical instrument having an overall shaft length of fifteen inches may have a reduced working length of about thirteen inches when placed through the seal housing of the prior art. That is, the working length is reduced by at least two inches. Moreover, there is the cost of complex seal housings to consider. In particular, they generally comprise a plurality of molded plastic components that address the complex nature of laparoscopic access devices. Accordingly, there is a need in the art for a surgical access device having integrated seals that does not require an external seal housing.